Many patents have been issued for end members for containers wherein the end member is provided with two openings, a main opening for removing the contents of the container and another opening serving to relieve pressure or vacuum within the container or to provide a vent. These patents fall into the following categories.
Pull tab completely removed: U.S. Pat. Nos. 3,221,924; 3,273,745; 3,301,434; 3,302,818; 3,307,737; 3,313,446; 3,326,405; 3,434,622; 3,441,167; 4,135,637; 4,405,056; 4,705,186;
Pressure relief and entire lid removed: U.S. Pat. Nos. 3,485,410; 3,593,876; 3,720,348;
Resealable tab: U.S. Pat. Nos. 3,804,287; 3,858,747; 4,572,398; 4,576,306;
Pull tab and panel removed: U.S. Pat. Nos. 3,627,168; 3,662,914;
Push in tab: U.S. Pat. Nos. 3,741,432; 3,880,316; 3,886,881; 3,888,199; 3,970,212; 3,982,657; 4,023,703; 4,032,034; 4,081,104; 4,105,134; 4,106,662; 4,119,050; 4,134,517; 4,136,797; 4,154,184; 4,155,480; 4,213,538; 4,355,935; 4,701,090.
For many years, the most commonly used beverage containers have end members with a stay on tab which is used to apply a force to a severable tab portion to form an opening in the end member and after such opening has been formed, both the severable tab portion and the stay on tab remain attached to the end member. To applicants' knowledge, no container end member having a stay on tab has been provided with means of some nature for forming a vent opening therein. While some consumers have used a "church key" to form such a vent opening, it is more desirable to have an easily openable vent opening formed in the end member so that the vent opening can be formed whenever desired.